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Lehs
  • Member for 9 years, 8 months
  • Last seen more than a week ago
  • Stockholm, Sweden
50 votes
3 answers
2k views

Any odd number is of form $a+b$ where $a^2+b^2$ is prime

21 votes
1 answer
2k views

Every prime number divide some sum of the first $k$ primes.

20 votes
0 answers
375 views

Does every power of two arise as the difference of two primes?

17 votes
3 answers
3k views

A topology on the set of lines?

16 votes
3 answers
517 views

Conjecture: $\pi(x)\ge \pi\circ\pi(x)+\pi\circ\pi\circ\pi(x)+\cdots$

16 votes
2 answers
589 views

A conjecture concerning primes and algebra

15 votes
1 answer
257 views

A conjecture about an unlimited path

14 votes
3 answers
535 views

Identities like $4+5+6=7+8$ and $10^2+11^2+12^2=13^2+14^2$ and so on...

14 votes
2 answers
524 views

Yet another conjecture about primes

14 votes
3 answers
1k views

A condition for being a prime: $\;\forall m,n\in\mathbb Z^+\!:\,p=m+n\implies \gcd(m,n)=1$

13 votes
6 answers
4k views

Is there a notation for being "a finite subset of"?

13 votes
1 answer
638 views

Mathematical disciplines with high thresholds

12 votes
1 answer
330 views

Conjecture about distribution of certain primes

12 votes
1 answer
1k views

Tensor products in general topology?

11 votes
1 answer
206 views

Conjecture: Every prime number is the difference between a prime number and a power of $2$

11 votes
1 answer
200 views

A conjecture about integer polynomials and primes

10 votes
2 answers
407 views

A conjecture about the prime function $p_n$: $p_m \cdot p_n >p_{m \cdot n}$

10 votes
3 answers
1k views

The difference of two coprime composites

9 votes
2 answers
469 views

Complete graphs in the plane with colored edges where an edge don't cross edges with same color

9 votes
2 answers
2k views

How do Gap generate the elements in permutation groups?

9 votes
2 answers
148 views

A familiar quasigroup - about independent axioms

8 votes
0 answers
557 views

Differences between set theory and second order logic?

8 votes
2 answers
393 views

Inequality $\varphi(N)>\pi(N)$?

8 votes
1 answer
1k views

A topology on the natural numbers: a set is closed if it contains the divisors of all its elements

8 votes
1 answer
747 views

Conjecture about primes and the factorial: for all primes $p>5$, must there exist a prime $q<p$ such that $q\equiv m!\pmod p$ for some $2<m<p$?

8 votes
1 answer
408 views

About the distribution of Gaussian prime pairs

8 votes
1 answer
1k views

Why should I learn modern category theory if my interest mainly is structured sets?

8 votes
2 answers
124 views

The set of primes of the form $a^2+8b^2$, where $a,b\in\mathbb N_+$

8 votes
2 answers
241 views

Most even numbers is a sum $a+b+c+d$ where $a^2+b^2+c^2=d^2$

8 votes
1 answer
98 views

The probability for a finite sequence to not include a prime

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